1. Field of the Invention
The present invention generally relates to a sealing device adapted to be disposed between inner and outer members rotatable relative to each other, for example, inner and outer races of a rolling contact bearing or between a rotary shaft and a housing through which the rotary shaft extends and, more particularly, to an improvement in and for the sealing device of a type utilizing a combination of a sealing plate such as a slinger and a sealing element including an elastic member.
2. Description of the Prior Art
This type of sealing device is disclosed in, for example, the Japanese Laid-open Patent Publication No. 57-103930 published in 1982, and is largely employed in various applications. This sealing device is reproduced in FIG. 8 and comprises, as shown therein, an annular sealing plate 51 of a generally L-shaped cross-section adapted to be fixedly mounted on the inner peripheral member, an annular sealing element 52 of a generally L-shaped cross-section adapted to be secured to the outer peripheral member and an elastic member 53 provided on the sealing element 52. The elastic member 53 has a side lip 54 and a radial lip 55 both formed integrally therewith. In an assembled condition, the sealing plate 51 and the sealing element 52 are positioned in face-to-face relation with each other with the elastic member 53 positioned between the sealing plate 51 and the sealing element 52. The side and radial lips 54 and 55 of the elastic member 53 are held in sliding contact with a radial wall 51b of the sealing plate 51 and a cylindrical sleeve 51 a of the sealing plate 51, respectively.
The prior art sealing device shown in FIG. 8 has been found to have a problem. Specifically, the prior art sealing device has no way of allowing a fluid medium such as muddy water, which has entered a space delimited between the sealing plate 51 and the sealing element 52, to be expelled to the outside. Therefore, the fluid medium once entering the space tends to be accumulated therein. The consequence is that the side lip 54 is kept immersed in the fluid medium accumulated within the space between the sealing plate 51 and the sealing element 52. For this reason, the side lip 54 seizes muddy particles and/or sands, eventually evolving heat which in turn results in incapability of sliding in contact with the radial wall of the sealing plate 51; This brings about reduction in sealing performance of the sealing device.